The present invention relates to a dispenser having an actuation recorder for recording the actuation profile thereof. In particular, the invention relates to metered dose inhalers by means of which medicaments contained in an aerosol container may be administered to a patient.
It is well known to treat patients with medicaments contained in an aerosol, for example, in bronchodilator therapy. It is also known to use for such therapy, medicaments which are contained in an aerosol and are administered to a patient by means of an inhalation device comprising a tubular housing or sleeve in which the aerosol container is located and an outlet tube leading out of the tubular housing. The aerosol containers used in such inhalation devices are designed to deliver a predetermined dose of medicament upon each actuation by means of an outlet valve member at one end which can be opened either by depressing the valve member while the container is held stationary or by depressing the container while the valve member is held stationary. In the use of such devices, the aerosol container is placed in the tubular housing with the outlet valve member of the container communicating via a support with the outlet tube, for example a nozzle or mouthpiece. When used for dispensing medicaments, for example in bronchodilation therapy, the housing is then held by the patient in a more or less upright condition and the mouthpiece or nozzle of the inhalation device is placed in the mouth or nose of the patient. The aerosol container is pressed towards the support to dispense a dose of medicament from the container which is then inhaled by the patient.
It may be understood that effective delivery of medicament to the patient using an inhalation device as described above is to an extent dependent on the patient""s ability to co-ordinate the actuation of the device (e.g. firing of the aerosol) with the taking of a sufficiently strong inward breath. The required coordination can present difficulties to some patients, with the risk that these patients do not receive the appropriate dose of medicament. It is thus desirable to provide a means for the patient to monitor their correct usage of the inhalation device. Such means might be designed for everyday usage, or for use in a system for training patients in the correct usage of the inhalation device.
The Applicants have now found that the actuation profile of an inhalation device may be effectively monitored by use of an inductive displacement transducer, which may simply be a coil of wire appropriately located within, or in some way associated with, the device. The coil may be connectable as the inductive element in an electronic circuit. On actuation of the device, the container is depressed and the change in inductance in the inductive element is measured. The measurements may be fed into an electronic processor, which itself may be connectable to a visual display unit which provides the advantage that the actuation profile may be visually displayed to the patient. The measurements may also be stored electronically for subsequent review and analysis.
One advantage of the use of the inductive displacement transducer to measure actuation profile is that there is no mechanical coupling of the container to the housing. Such additional mechanical coupling is inevitable in the use of switches or mechanical devices to monitor actuation.
The inductive displacement transducer may be directly attached to the housing of the dispenser. Alternatively, the inductive displacement transducer may be mounted on a carrier, which is mountable on the dispenser but separable therefrom. Where a carrier mounting is employed it would be usual to shape the carrier to be readily receivable by the housing of a standard metered dose inhaler as a removable xe2x80x98add onxe2x80x99 thereto.
The Applicants have also found that the airflow across the dispensing part of the device may be monitored by use of a pressure transducer, which measures the pressure drop across the inhaler device. In a simple embodiment, the pressure transducer is also connectable via circuitry to a visual display unit to provide a visual display of the inhalation profile, and optionally of the actuation pressure profile to the patient.
EP-A-387,222 describes an inhalation device having a detector for detecting the airflow of the inhalation and the availability of medicament at the time of inhalation. The detector can be a microphone or a pressure detector. No mention is made of the use of a displacement transducer as a detection device. Further, no mention is made of the problem of monitoring the actuation profile (versus the inhalation profile) of the device, as is addressed by the presently described invention.
U.S. Pat. No. 5,676,129 describes an inhalation device having a pressure sensor to measure pressure changes in the transfer channel of the mouthpiece of a metered dose inhaler, thereby providing a means of counting the number of doses dispensed. No mention is made of the use of a displacement transducer as a detector. No mention is made of the use of visual display of pressure profile in the training of patients in correct device usage.
It is an object to provide a dispenser having an actuation indicator which allows for patient and physician monitoring of the actuation profile and which can be employed in a system to be used in training the patient in the correct usage of the dispenser.
According to one aspect of the present invention there is provided a dispenser for dispensing medicament comprising a housing having a support; a container, locatable within said housing, having an outlet member, wherein said container is movable relative to the housing to enable dispensing therefrom and said outlet member is connectable with said support to prevent relative movement therebetween; and an inductive displacement transducer including one or more inductive elements, wherein said container is comprised of, or has attached thereto a component comprised of a material capable of disturbing the magnetic field creatable by the flow of electric current in said one or more inductive elements.
The inductive displacement transducer uses an inductive element to measure the position of the container relative to the housing. Since the inductive displacement transducer measures the relative proximity of the container to the housing it may also be thought of as an inductive proximity detector.
The container may have properties such that movement thereof relative to the one or more inductive elements is capable of causing a change in the inductance therein. The container may, for example, be comprised of a magnetic or electronically conductive material such as aluminium, or alternatively the container may have attached thereto a magnetic or electronically conductive component. The component may, for example, be a ring of material such as a ferrite ring or the component may be a coating or covering of suitable material.
Suitably, the inductive displacement transducer is engagable with the housing, such as with the exterior of the housing.
Suitably, the inductive displacement transducer is provided with mounting means for mounting of the inductive displacement transducer to the housing.
Preferably, the mounting means comprises a carrier sleeve mountable on the exterior of the housing and separable therefrom.
Suitably, the inductive displacement transducer has a plurality of inductive elements, wherein the inductive elements are magnetically or electronically couplable to each other.
Suitably, the container is an aerosol container.
Suitably, the housing is provided with an outlet, more preferably in the form of a mouthpiece. Preferably, the dispenser comprises a passage through which dispensed doses may pass from the container to the outlet.
Suitably, the container provides measured doses.
Suitably, the inductive elements comprise an electrically conductive material. In one aspect the electronically conductive material is a metal, more preferably copper or stainless steel. In another aspect the electrically conductive material is a conductive polymeric material.
The electrically conductive material is connectable as the inductive element in an electronic circuit, preferably an oscillator circuit or an AC bridge circuit. Preferably, the electronic circuit operates at a frequency of from 0.1 to 100 MHz, more-preferably 0.2 to 10 MHz.
In one aspect the electronically conductive material is a wire or tape formed into a coil. The coil may be a flat coil or may be a helical coil. Arrangements of flat or helical coils are envisaged. The turns of the coil may be electrically insulated from each other by the presence of an electrically insulating coating or by embedding in electrically insulating materials or by choice of sufficient spacing of the coils such that the air between the turns of the coil acts as an electrical insulator.
Suitably, the dispenser additionally comprises a pressure transducer.
Suitably, the dispenser is a breath operated inhaler which is actuable in response to the inward breath of a user.
According to another aspect of the present invention there is provided a system for training users in the operation of a dispenser comprising a dispenser as described above in communication with a visual unit capable of visually indicating actuation of the device by a user.
According to a further aspect of the present invention there is provided an actuation indicating device for use with a dispenser comprising a housing and a container, locatable within said housing, having an outlet member, the actuation indicating device comprising an inductive displacement transducer having mounting means to enable mounting to the housing.
In one aspect, the device records and displays the number of doses of medicament dispensed or remaining within the container following actuation thereof.
In another aspect, the device displays a symbol indicating that actuation has occurred.
In one aspect, the mounting means comprises a grip member which is engagable with the housing, preferably with the exterior of the housing.
In another aspect, the mounting means comprises a carrier sleeve mountable on the exterior of the housing and separable therefrom. A pressure transducer may also be mountable to the carrier sleeve.
The actuation indicating device and dispenser may be suppliable as a kit of parts.
According to a yet further aspect of the present invention there is provided the use of an inductive displacement transducer including one or more inductive elements to detect actuation of a dispenser for dispensing medicament, said dispenser comprising a container locatable within a housing, wherein said container is movable relative to the housing to enable dispensing therefrom, and wherein said container is comprised of, or has attached thereto a component comprised of, a material capable of disturbing the magnetic field creatable by the flow of electric current in said one or more inductive elements.